As known in the art of internal combustion engines, a distributor is typically a rotary switch which directs a high-voltage ignition current in proper sequence to the various cylinders of the engine. In motor vehicles such as automobiles, the distributor generally includes an apparatus for timing the ignition to occur when each piston is at a predetermined position in the cycle, usually near the top of the cylinder. The apparatus usually includes breaker points, which are a set of cam-operated contacts which trigger the ignition pulse when opened. Timing of the opening of the breaker points is controlled by a diaphragm responsive to pressure in the engine's intake manifold so that timing is altered at higher engine speeds (RPM) and at higher engine loads.
Typical distributors in current use suffer from what is known as inductive hysteresis. This is a phenomenon in which ignition timing is retarded, rather than advanced, as engine speeds approach and exceed 7000 RPM. Conventional distributors rely on mechanical devices with a balance of forces including spinning weights working against spring tension causing a moveable plate to change the position of the triggering mechanism to achieve an engine-speed compensating ignition advance. The inaccuracies of springs (both in manufacture and due to wear from use) and the clearances necessary in the moveable mechanism prohibit the accuracy of ±½ A engine degree at most any engine speed.